tap: Convert tap6_handler() to iov_tail

Use packet_data() and extract headers using IOV_REMOVE_HEADER()
and IOV_PEEK_HEADER() rather than packet_get().

Remove packet_get() as it is not used anymore.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

3 files changed, 16 insertions, 90 deletions

diff --git a/packet.c b/packet.c
index 014b353..5da18ba 100644
--- a/packet.c
+++ b/packet.c
@@ -122,76 +122,6 @@ void packet_add_do(struct pool *p, struct iov_tail *data,
 }
 
 /**
- * packet_get_try_do() - Get data range from packet descriptor from given pool
- * @p:		Packet pool
- * @idx:	Index of packet descriptor in pool
- * @offset:	Offset of data range in packet descriptor
- * @len:	Length of desired data range
- * @left:	Length of available data after range, set on return, can be NULL
- * @func:	For tracing: name of calling function
- * @line:	For tracing: caller line of function call
- *
- * Return: pointer to start of data range, NULL on invalid range or descriptor
- */
-/* cppcheck-suppress [staticFunction] */
-void *packet_get_try_do(const struct pool *p, size_t idx, size_t offset,
-			size_t len, size_t *left, const char *func, int line)
-{
-	char *ptr;
-
-	ASSERT_WITH_MSG(p->count <= p->size,
-			"Corrupt pool count: %zu, size: %zu, %s:%i",
-			p->count, p->size, func, line);
-
-	if (idx >= p->count) {
-		debug("packet %zu from pool count: %zu, %s:%i",
-		      idx, p->count, func, line);
-		return NULL;
-	}
-
-	if (offset > p->pkt[idx].iov_len ||
-	    len > (p->pkt[idx].iov_len - offset))
-		return NULL;
-
-	ptr = (char *)p->pkt[idx].iov_base + offset;
-
-	ASSERT_WITH_MSG(!packet_check_range(p, ptr, len, func, line),
-			"Corrupt packet pool, %s:%i", func, line);
-
-	if (left)
-		*left = p->pkt[idx].iov_len - offset - len;
-
-	return ptr;
-}
-
-/**
- * packet_get_do() - Get data range from packet descriptor from given pool
- * @p:		Packet pool
- * @idx:	Index of packet descriptor in pool
- * @offset:	Offset of data range in packet descriptor
- * @len:	Length of desired data range
- * @left:	Length of available data after range, set on return, can be NULL
- * @func:	For tracing: name of calling function
- * @line:	For tracing: caller line of function call
- *
- * Return: as packet_get_try_do() but log a trace message when returning NULL
- */
-void *packet_get_do(const struct pool *p, const size_t idx,
-		    size_t offset, size_t len, size_t *left,
-		    const char *func, int line)
-{
-	void *r = packet_get_try_do(p, idx, offset, len, left, func, line);
-
-	if (!r) {
-		trace("missing packet data length %zu, offset %zu from "
-		      "length %zu, %s:%i",
-		      len, offset, p->pkt[idx].iov_len, func, line);
-	}
-
-	return r;
-}
-
-/**
  * packet_data_do() - Get data range from packet descriptor from given pool
  * @p:		Packet pool
  * @idx:	Index of packet descriptor in pool
diff --git a/packet.h b/packet.h
index 062afb9..dab8274 100644
--- a/packet.h
+++ b/packet.h
@@ -33,12 +33,6 @@ struct pool {
 int vu_packet_check_range(void *buf, const char *ptr, size_t len);
 void packet_add_do(struct pool *p, struct iov_tail *data,
 		   const char *func, int line);
-void *packet_get_try_do(const struct pool *p, const size_t idx,
-			size_t offset, size_t len, size_t *left,
-			const char *func, int line);
-void *packet_get_do(const struct pool *p, const size_t idx,
-		    size_t offset, size_t len, size_t *left,
-		    const char *func, int line);
 bool packet_data_do(const struct pool *p, const size_t idx,
 		    struct iov_tail *data,
 		    const char *func, int line);
@@ -47,11 +41,6 @@ void pool_flush(struct pool *p);
 
 #define packet_add(p, data)					\
 	packet_add_do(p, data, __func__, __LINE__)
-
-#define packet_get_try(p, idx, offset, len, left)			\
-	packet_get_try_do(p, idx, offset, len, left, __func__, __LINE__)
-#define packet_get(p, idx, offset, len, left)				\
-	packet_get_do(p, idx, offset, len, left, __func__, __LINE__)
 #define packet_data(p, idx, data)					\
 	packet_data_do(p, idx, data, __func__, __LINE__)
 
diff --git a/tap.c b/tap.c
index bb18b76..5010c45 100644
--- a/tap.c
+++ b/tap.c
@@ -896,21 +896,28 @@ resume:
 	for (seq_count = 0, seq = NULL; i < in->count; i++) {
 		size_t l4len, plen, check;
 		struct in6_addr *saddr, *daddr;
+		struct ipv6hdr ip6h_storage;
+		struct ethhdr eh_storage;
+		struct udphdr uh_storage;
 		const struct ethhdr *eh;
 		const struct udphdr *uh;
 		struct iov_tail data;
 		struct ipv6hdr *ip6h;
 		uint8_t proto;
-		char *l4h;
 
-		eh =   packet_get(in, i, 0,		sizeof(*eh), NULL);
+		if (!packet_data(in, i, &data))
+			return -1;
+
+		eh = IOV_REMOVE_HEADER(&data, eh_storage);
 		if (!eh)
 			continue;
 
-		ip6h = packet_get(in, i, sizeof(*eh),	sizeof(*ip6h), &check);
+		ip6h = IOV_PEEK_HEADER(&data, ip6h_storage);
 		if (!ip6h)
 			continue;
 
+		check = iov_tail_size(&data) - sizeof(*ip6h);
+
 		saddr = &ip6h->saddr;
 		daddr = &ip6h->daddr;
 
@@ -918,10 +925,8 @@ resume:
 		if (plen != check)
 			continue;
 
-		data = IOV_TAIL_FROM_BUF(ip6h, sizeof(*ip6h) + check, 0);
 		if (!ipv6_l4hdr(&data, &proto, &l4len))
 			continue;
-		l4h = (char *)data.iov[0].iov_base + data.off;
 
 		if (IN6_IS_ADDR_LOOPBACK(saddr) || IN6_IS_ADDR_LOOPBACK(daddr)) {
 			char sstr[INET6_ADDRSTRLEN], dstr[INET6_ADDRSTRLEN];
@@ -946,6 +951,8 @@ resume:
 		}
 
 		if (proto == IPPROTO_ICMPV6) {
+			struct icmp6hdr l4h_storage;
+			const struct icmp6hdr *l4h;
 			PACKET_POOL_P(pkt, 1, in->buf, in->buf_size);
 
 			if (c->no_icmp)
@@ -954,9 +961,9 @@ resume:
 			if (l4len < sizeof(struct icmp6hdr))
 				continue;
 
-			data = IOV_TAIL_FROM_BUF(l4h, l4len, 0);
 			packet_add(pkt, &data);
 
+			l4h = IOV_PEEK_HEADER(&data, l4h_storage);
 			if (ndp(c, (struct icmp6hdr *)l4h, saddr, pkt))
 				continue;
 
@@ -969,12 +976,13 @@ resume:
 
 		if (l4len < sizeof(*uh))
 			continue;
-		uh = (struct udphdr *)l4h;
+		uh = IOV_PEEK_HEADER(&data, uh_storage);
+		if (!uh)
+			continue;
 
 		if (proto == IPPROTO_UDP) {
 			PACKET_POOL_P(pkt, 1, in->buf, in->buf_size);
 
-			data = IOV_TAIL_FROM_BUF(l4h, l4len, 0);
 			packet_add(pkt, &data);
 
 			if (dhcpv6(c, pkt, saddr, daddr))
@@ -1031,7 +1039,6 @@ resume:
 #undef L4_SET
 
 append:
-		data = IOV_TAIL_FROM_BUF(l4h, l4len, 0);
 		packet_add((struct pool *)&seq->p, &data);
 	}